Tripping mechanism for printing presses



Oct. 21, 1930. v H. FISCHER 1,779,310

TRIPPING MECHANISM FOR PRINTING PRESSES V Fild Nov. 6. 1929 Patented Oct. 21, 1930 I UNITED STATES PATENT oFncr:

HANS IISCHER, OF AUGSBUR G, GERMANY, ASSIGNOR TO MASGHINENFABRIK AUGS- BURG-NURNBERG A. G., AUGSBUBG, GERMANY, A CORPORATION OF GERMANY TRIPPING MECHANISM FOR PRINTING PRESSES Application filed November 6, 1929, Serial No. 405,128, and in Germany October 13, 1928. I

Mechanically or electrically operated devices for tripping the cylinders of rotary printing machines in case the sheet to be printed fails to be fed at all or fails to be fed properly, are known. Mechanisms are also known which throw the printing cylinders off impression if a sheet fails to be fed, and automatically throw them on impression again as the next sheet is fed. In both kinds feelers. Where both operations are controlled automatically the mechanism is rather complicated as a great number of mechanical parts is necessary to make the movement of the feeler actuate the tripping mechanism proper.

The object of this invention is to provide novel mechanism whereby both operations, the throwing off impression and the throwing on impression are initiated by means of electromagnets. According to the invention the throw-on magnet is energized as a result of the motion carried out by the throwing-off mechanism in tripping, so that as soonas a sheet is fed, and the sheet slips between feeler and contact plate and so interrupts the circuit of the throw-off magnet, the throw-on magnet may then attract its armature and thereby initiate the throwing on operation. Comformable to this purpose the armatures of the magnets are disposed in such a way on opposite ends of a common lever which aetuates the tripping, that when first the throw-ofi' magnet is energized and 10 of tripping devices use is made of mechanical 1 attracts its armature this causes the lever.

toswing whereby the circuit of the throwon magnet also is closed and the throw-on magnet .energized. The throw-on magnet can however cause the armature carrying lever to swing back only when the current flowing through the coil of the throw-off magnet is interrupted in consequence of a sheet being fed and thereby interposed between feeler and contact plate.

The invention is particularly advantageous when applied to multi-colour printing machines. The perfectly automatic throwing on impression after an interruption in the feeding of sheets is in such cases particularly valuable because it relieves the machine operator of the labour of attending to each separate printing mechanism successively thrown off impression after a sheet has failed to be fed at one of them. Conformable to the purpose each separate printing mechanism of a multicolour machine is fitted with a separate tripping mechanism according to the invention, so'that each may operate perfectly independently from the others.

Fig. 1 of the drawing is a side elevational view, mainly diagrammatical, of a sheetfed.

rotary photogravure printing press, the printing mechanisms of which are equipped with a preferred constructional formof the novel tripping mechanism.

Fig. 2 isa similar but more detailed view of a printing mechanism so equipped. In multicolour printing machines the tripping device of each printing mechanism operates independently of the others.

In the drawing 1 is the impression cylinder and 2 the feed table. Forme cylinder" 3 is journalled in known manner in eccentric bushes or bearings and may be thrown off impression by means of lever 4 which is pivotally connected with a rod 5 theother end of which is pivotally connected with a lever 6 mounted fast on shaft 8. Adjacentthereto a notched disk 7 is mounted fast on the same shaft 8. The shaft may be rocked by means of a clutch or pawl 9 on the end of lever 10 which is loosely mounted on shaft 8. Actuated by link 11, bell crank lever 12 and cam 13 on impresslon cylinder 1, lever 10 rocks to and fro once' during each revolution of the cylinder.

If magnet 14 is energized and attracts its armature 15,

to the left and curved guide plate 18 which lever 16 pivoted at 17 will swing is fast on the end of lever 16 will push roll 19 on the end of lever 20 in the same direction. Clutch 9 which is fastened to the other end of lever 20, which end is pivoted to arm 10, is thereby caused to tilt and engage the right hand shoulder 21 of the notch of disk 7. During the next upward rocking movement of clutch 9, shaft 8 is consequently rocked clock-wise and rod 5 throws forme cylinder 3 off impression.

'If however magnet 22 attracts its armature 23 lever 16 will swing to the right, clutch 9 is tilted to the left, engages the left hand shoulder 24 of the notch, thereby rocking shaft 8 counterclockwise and forme cylinder 3 is thrown on impression again.

Magnets 14 and 22 are controlled as follows. Above a metallic contact plate 29 a feeler 28 is disposed which in known manner swings to and fro once during each revolution of the impression cylinder, thereby contactin with plate 29 whenever a sheet is due to be ed. Plate 29 through lead 30 is connected to one lead 30 of the supply line of the source of current. By means of lead 25, contacting piece 25, switch 26 and lead 27 one pole of magnet 14 is connected to the other lead 27 of the supply line of the source of current; the other pole of magnet 14 is connected by lead 28 with feeler 28. If no sheet is fed and the feeler consequently touches plate 29,magnet 14 is energized, attracts armature l5, and forme cylinder 3 is thrown off impression. In such case, current flows from line 27 through lead 27, switch arm 26, contact 25, lead 25, magnet 14, through the wire 28 to feeler 28, thence through feeler 28 to plate 29, and through the lead 30 to the other side of the line 30.

By means of lead 31', contacting piece 31, switch 26, and lead 27, one pole of magnet 22 is also connected with lead 27. The other pole of its coil is connected by lead 35 with contacting spring 32 which slides on contacting ring segment 33 carried by shaft 8. On this segment 33 a second contacting spring 34 slides, which is connected by lead 35 with contacting spring 35 which in turn slides on contacting ring segment 36 on axle 37 of the impression cylinder, the segment 36 being connected by lead 36 with lead 30' which in turn connects to the other lead 30 of the supply line and completes the electrical circuit of magnet 22. Contacting segment 33 connects springs 32 and 34 only after shaft 8 has been rocked to the .right and the forme cylinder has been thrown off impression, that is after magnet 14 has attracted armature 15. When shaft 8 has thus been rocked so that the segment 33 connects brushes 32 and 34, and while contacting spring 35 slides on segment 36 during rotation of impression cylinder 1, the coil of magnet 22 in this phase is traversed by a current at every revolution of the impression cylinder, this current flowing from line 27 through lead 27', switch arm 26, contact I 31, lead 31', magnet 22, lead wire 32 and brush 32, segment 33, brush 34, lead wire 35' and brush 35, segment 36, lead wire 36, and lead Wire 30 back to the other side of the line 30. Magnet 22 is consequently energized but cannot attract armature 23 because the air gap between magnet 22 and armature 23 is too large to overcome the attraction of armature 15 to magnet 14 which is also energized at this time. Now as soon as a sheet is properly fed, it passes between feeler 28 and plate 29 and breaks contact between feeler 28 and contacting plate The current flowing through coil 14 is thus interrupted, and magnet 22 then attracts armature 23 and swings lever 16 to the right, thus rocking pawl 9 into position to engage shoulder 24 of disk 7 to thereby rock shaft 8 counterclockwise, and the forme cylinder is thrown on impression again.

Contact between feeler 28 and plate 29 lasts longer and starts earlier than contact between spring 35 and segment 36. If a sheet fails to be, fed, throw-off magnet 14 is consequently energized earlier than throwon magnet 22, the current flowing through throw-oncoil 22 cannot overcome the magnetic attraction for armature 15 by coil 14 as long as this coil remains energized, and lever 16 remains in the thrown-off position imparted to it by magnet 14.

Switch lever 26 may be swung into either of three positions: To the left, contacting with piece 25 only; to the right, contacting with piece 31 only, or a middle position where it contacts with both. \Vhile making ready, lever 26 is switched to contacting piece 25 and the forme cylinder in consequence remains permanently thrown off impression. At times it is desirable to throw on impression but without feeding sheets to the inipression cylinder; in this case lever 26 is switched to 31. Ordinarily lever 26 will occupy the middle position as shown in the drawing, which permits either of the magnets to operate.

The invention is not restricted to photogravure printing presses, but may be applied to all kinds of printing presses where throwing off impression is desirable in case sheets fail to be fed.

What I claim is:

1. In a sheet fed rotary printing press, having a forme cylinder and an impression cylinder; means for throwing the forme cylinder off and on impression including a rock lever, an armature on said rock lever, an electromagnet adapted .to attract said armature and thereby initiate the operation of throwing said forme cylinder ofi' in'lpression, a second armature on said rock lover, a second electromagnet adapted to attract said second armature and thereby initiate the operation of of current, a lead connecting said contact plate with the source of current, a contact ring segment on said impression cyl1nder,'a

' lead connecting. said ring segment and said contact plate, a contact spring sliding on said ring segment, a rock shaft, a second contact ring segment on said rock shaft a second contact spring permanently contacting with said second ring segment, a lead connecting said contact springs, a third contact spring adapted to contact with said second ring segment, an electromagnet, a lead. connecting said third contact spring and said electromagnet, a contact piece, a lead connecting said contact piece and said electromagnet, a switch lever adapted to contact with said contact piece, and a lead connecting said switch lever with the source of current,

3. In a'sheet fed rotary printing press, having an impression cylinder and a forme cylinder; a feed table, a contact plate on said feed table, a feeler adapted to contact with said plate when a sheet fails to be fed, an electromagnet, a lead connecting said feeler and said electromagnet, a contact piece, a lead connecting said contact piece and said electromagnet, aJsWitCh lever adapted to contact with said contact piece, a source of current, a lead connecting said switch lever with said source of current, and interconnections actuated by said electro-magnet and rendered operative when said feeler contacts with said contact plate to energize the electric circuit of said magnet to move said impression cylinder and said forme cylinder relatively to each other out of printing contact.

4. In a printing press of the character described, having an impression member, a forme member, and means for feeding sheets thereto; automatically operating electrical means responsive to the sheet feeding means for effecting relative movement between the said impression member and the forme member to prevent printing contact therebetween when a sheet fails to be fed thereto, and automatically operating electrical means for returning said impression member and said forme member into printing contact when a sheet is thereafter properly fed thereto.

5. In a printing press of the character described, having an impression member, a forme member, and means for feeding sheets thereto; automatically operating electrical means responsive to the sheet feeding means for efiecting relative movement between the said lmpression member and the forme member to prevent printing contact therebetween when a sheet fails to be fed'thereto, automatically operating electrical means for returning said impression member and said forme member into printing contact when a sheet is thereafter properly fed thereto, and means for maintaining said last mentioned electrical means temporarily inoperative as long as sheets are properly fed thereto, and for bringing said last mentioned electrical means into operation only after said first mentioned electrical means has been brought into operation by'a failure of the sheet feeding means.

6. In a rotary printing press of the character described, having an impression cylinder, a forme cylinder, and means for feeding sheets thereto; automatically operating electromagnetic means responsive to the sheet feeding means for effecting relative movement between the said impression cylinder and the forme cylinder to prevent printing contact therebetween'when a sheet fails to be fed to said impression cylinder, a second automatically operating electromagnetic means brought into operation only after said first mentioned electromagnetic means has been energized upon a failure of the sheet feeding means, an operative interconnection between said first mentioned electromagnetic means and said second electromagnetic means, the first mentioned electromagnetic means remaining operative through said connection to prevent actuation by said second electromagnetic means when energized as long as sheets fail to be fed to said impression cylinder, said first mentioned electromagnetic means being deencrgized when a sheet is thereafter properly fed to said imprcssion cylinder, whereby said second electromagnetic means is then rendered operative,

to effect return movement of said forme cylinder andimpression cylinder into printing en-' gagement.

' '7. In a rotary printing press of the char'acter described, having an impression cylinder, a forme cylinder, and means for feeding sheets thereto; a movable member, operative connections from said movable member for effecting relative movement betweensaid forme cylinder and said impression cylinder to throw said forme cylinder on and off impression, electromagnetic means associated with said movable member and automatically responsive to said sheet feeding means to be energized by a failure of the sheet feeding means to feed a sheet to said impression cylinder to thereby effect movement of said movable member in one direction to throw said forme cylinder off impresion, a second electromagnetic means associated with said movable member and automatically brought into operative relation, after actuation by said first'mentioned electromagnetic means with resultant throwing of the forme cylinder off impression, by the feeding thereafter of a sheet to said impression cylinder, whereby said second electromagnetic means effects movement of said movable member in the opposite direction to again throw said forme cylinder on impression.

8. In a sheet fed rotary printing press, having a forme cylinder and an impression cylinder; automatically operating means including an electro-magnet for moving the forme cylinder out of printing contact with said impression cylinder when a sheet fails to be fed, and automatically operating means including an electro-magnet for moving the forme cylinder into printing contact with said impression cylinder when a sheet is thereafter properly fed. to the impression ,cylinder.

9. In a sheet fed rotary printing press, having a forme cylinder and an impression cylinder; means for moving said forme cylinder and impression cylinder relatively to each other into and out of printing contact comprising, a cam on said impression cylinder, a bell crank lever operated by said cam, a rock shaft, a lever mounted for free pivotal movement on said rock shaft, a notched disk on said rock shaft, a clutch pivotally connected with said lever and adapted to tilt to thereby engage with said notched disk and rock said rock shaft, a link pivotally connected to said lever and connected to said clutch, automatically operating electro-magnctic means for actuating said link to thereby tilt said clutch when a sheet fails to be fed, and operative interconnections responsive to the movement of said rock shaft for effecting relative movement of the forme cylinder and the impression cylinder to thereby move them into or out of printing contact.

10. In a sheet fed rotary printing press, having an impression cylinder and a forme cylinder journalled in eccentric bushes; means for moving said forme cylinder into or out of printing engagement with said impression cylinder comprising, a lever for revolving said bushes, a rock shaft, a lever on said rock shaft, a rod pivotally connecting said levers, and automatically operating means including an electro-magnet for rocking said shaft to thereby trip said forme cylinder when a sheet fails to be fed.

-11. In a sheet fed multicolour printing press having a plurality of printing mechanisms, each printing mechanism including an impression cylinder and a forme cylinder; automatically operating means including an electro-magnet for each printing mechanism for moving the said forme cylinder and impression cylinder of the respective printing mechanism relatively to each other out of printing engagement when a sheet fails to be fed to the respective impression cylinder, and automatically operating means including an electro-magnet for each printing mechanism for moving the said forme cylin P the said automatically operating means for another of-the said printing mechanisms.

In testimony whereof I have affixed my signature,

HANS FISCHER. 

